Hexagon nuts ~0,8d DIN 934-aluminium M4

The wrench sizes for hexagon bolts and nuts are specified in ISO 272: 1982-01. The nominal wrench size on the workpiece (e.g. bolt, nut) is the same as that on the tool. However, there is some play between the two to allow the tool to be fitted without difficulty. The relationship between the nominal diameter d of the thread and the wrench size s is standardised in EN ISO 4014 and EN ISO 4017 for hexagon bolts, and in EN ISO 4032 for hexagon nuts (dimensions in mm).

Aluminum is a silvery-white light metal with one third the density of steel. In materials engineering, “aluminum” refers to all materials based on the element aluminum. This includes pure aluminum (at least 99.0 % Al), ultra-pure aluminum (at least 99.7 % Al) and, in particular, aluminum alloys, which have strengths comparable to steel. Aluminum alloys are divided into wrought alloys and cast alloys depending on how they are produced.

The term plain indicates a completely untreated, merely oiled, smooth surface for all DIN and ISO screws such as wood screws, hexagon head screws, threaded rods, nuts and many types of washers.